


Changing what's inside

by SecretGarden03



Category: Undertale (Video Game)
Genre: Alternate Universe - Gaster Blaster (Undertale), Alternate Universe - Underfell, Angst and Fluff and Smut, F/F, F/M, Language, M/M, Other Additional Tags to Be Added, Secrets
Language: English
Status: In-Progress
Published: 2017-12-22
Updated: 2017-12-24
Packaged: 2019-02-08 23:35:25
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 2
Words: 1,560
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12875451
Author URL: https://archiveofourown.org/users/SecretGarden03/pseuds/SecretGarden03
Summary: When Sans is at us sentry station it's just an ordinary day ......  right??????WRONGWhen he finds another version of himself from a 'Kill Or Be Killed' world, can be change the others perspective on the world they both live in???????Can he tell you his (and his brothers) greatest secret???????P.S. sorry if the summary and spellings are bad





	1. Unexpected Meeting

**Author's Note:**

> Hi guys I am so glad I can write this chapter for you all and I hope that you guys will enjoy it.
> 
> This is the first fan-fic I have ever written and if there are any spellings or other errors please point them out for me and I hope you guys enjoy.

**Summary for the Chapter:**

> When Sans is at his sentry station it's just an ordinary day ...... right??????  
> WRONG  
> When he finds another version of himself from a 'Kill Or Be Killed' world, can be change the others perspective on the world they both live in???????  
> Can he tell them his (and his brothers) greatest secret???????

**Notes for the Chapter:**

> Hi guys I am so glad I can write this chapter for you all and I hope that you guys will enjoy it.
> 
> This is the first fan-fic I have ever written and if there are any spellings or other errors please point them out for me and I hope you guys enjoy.

For Sans it was just another day  ~~reset~~. But this one felt different somehow. He couldn't tell how but it just felt off...

His nerves were starting to get to him. His tail wrapped around a leg if the stool he was sitting on to stop it from twitching.

Suddenly there was a burst of red light from behind him and he had his magic ready on the defensive in case they decided to attack. As he heard the mysterious monster get up with a huff, he deciding to seek on all fours to get a closer look. When he was able to see the monster more clearly he saw a large crack up his left eye socket, shark-like teeth with one gold tooth. He was wearing a black leather jacket with a fur lines hood, red jumper, black shorts with a yellow stripe down the side and black trainers with untied laces. You were easily taller than him by a good foot 'n' a half.

He slowly approached him making your presence clear. He turned around and spotted you. The magic radiating off him was the intent to kill and he used his magic to push calming and non threatening intent but putting much power into it so he knows not to try anything.

He doesn't look pleased with you. It's them you realised something ......

............

..............

............

..........

He is another Sans...

He huffed out a breath of air and start to stand up slowly as to not frighten or intimidate the other. When he takes a couple of hesitant steps forward he growl at the other, warning the other not to come any closer. He hears this and just smirks. Ok he is really starting to get on his nerves now.

"who the fuck are yer??????" The other said which surprised him but he didn't flinch away from him. Instead he answered the question.

"I'm Sans, Sans the skeleton. and you are?????" He knew exactly who it was it was himself from another universe and it looked like a violent one at that.

Instead of answering he just stood there. He felt a check pulse through him showing his stats to the other.

 

**Sans**

 

**LV 1Aa**

**HP 14**

**AT 33**

**DF 38**

***Looks can be deceiving**

 

He saw the others eye lights expand slightly in shock of his stats and decided to return the favour.

 

**Sans**

 

**LV 7**

**HP 37**

**AT 55**

**DF 48**

***Bark is worse than his bite**

 

To see himself with LV shocked him but he expected it so kept a level head about it.

 The other got into a defensive stance expecting a fight. However he did not start attacking, he just stood there, staring at each other.

In the distance he could hear his brother trudging through the snow just passing Doggo's station. He turned his head and listened intently to their conversation that was nothing but mumbling to him despite his better hearing.

When he turned. His attention back to the other he was surprised to see that his counterpart has gone.

............

OF COURSE THE OTHER VERSION OF HIMSELF CAN TELEPORT!!!!! WHY THE HELL WAS HE SURPRISED!!!!

He let out a annoyed sigh teleported back to his sentry station and listened as his brother was passing by his station.

 

* * *

 

 

He was completely unaware of the crimson eye-lights watching him and his interaction.

 

 

Studying him for any weakness other than Papyrus.

 

 

After all .......he didn't want to hurt his brother.....

**Notes for the Chapter:**

> Oooooook.
> 
> Editing is done for this chapter
> 
> 29/12/2017


	2. Looking for his counterpart

**Summary for the Chapter:**

> Lots of planning goes down.....  
> Lots of mystery.......

When Sans got home he decided to make a plan. He knew that if the other didn't want to be found then he wouldn't, but there would be one way to ......  NO what was he thinking revealing his and his brothers secret like that. He was starting to get annoyed at himself for being so good at keeping away from others and his own magical ability.

But if this really was another version of himself then that would mean...... UUUUUUUUGGGGGHHHHHH!!!! Why couldn't he stop thinking about that. He might not even be able to do that!!!!

This was getting frustrating. He needs to find him before nightfall. If he doesn't then the only way for his alternate to survive the night is if he was in a tree above the ground.

.......

........

.........

....

Wait. The one place that the other would probably go (if it was in his world) would be Grillby's. He trusted Grillby. Check he raised him and Papyrus after all he was basically their father after..... NO . No time to think about that now.

He could ask around although he doubted that his other would go there. He could also ask the Dog-Guard to keep an eye out for him... Maybe ask Alphys but he doubted that it would stay between them and she would say something to Undyne and she would say something to Papyrus and he wanted to tell him himself before he found his counterpart.

That would actually work.

He would talk to them tomorrow, but for now he was going to go to Grillby's to talk to the Guard and Grillby.

 

* * *

 

 

He needed to be careful....

This is not his world......

He knows nothing of this world......

 

HIS ALTERNATE SELF (and his brother) HAVE A TAIL!!!!!!!!!!

 

He needs to be careful......

Lay low for a while....

Maybe go to Grillby's.....?

.....yeah......

.......after everything has calmed down..........

He needs to wait......

He needs to observe.......

He needs to create a shelter and find food........

He has no idea how long he is staying hear for......

Needs to be off the ground...........for some reason......he doesn't feel like it's safe on the ground during the night......

He needs to lay low....

Not be seen....

Stay in the shadows....

But for some reason he is pulled to town......

Pulled to his alternates home.....

Like its the safest place to be.....

Like he needs to get out of this forest.......it doesn't seem safe......

................

.............

NO!!! It's just a forest!!!!! Nothing is in hear.....!!!!!

But that doesn't stop the feeling of danger is in this forest................

 

* * *

 

As he walked into Grillby's the hole place was buzzing with positive energy. He walked o the bar and was greeted by, the fire elemental, Grillby, his father, his family.

As soon as he entered the bar Grillby noticed his expression as soon as he opened the door. He was frustrated. 

"heya, Grillby. "he noticed the look Grillby was giving him *sigh* "yeah,yeah, I need to tell you and the Dog-Guard about this."

As he told Grillby and the Dogi about the other version of himself from an alternate universe and what he looked like. Warning them of the others LV. When he had finished his explanation the Dogi told the other members of the Dog-Guard and they all agreed to help and promised not to tell Alphys, Undyne and Papyrus as long as he told them tomorrow and that is what he was going to do.

After that was done his phone rang.

"Sans, I need to tell you something"

"what's up Alph??"

"There's someone acting strange in the woods in the south clearing close to were THEY are usually active and you are the fastest person to get there. He looks kinda like you an-" she was interrupted but Sans

"Call Undyne and Papyrus over to the labs and tell Papyrus 'the cats is out of the bag' he will understand what I mean but tell him to wait until I come back for an explanation."

After that he hung up before getting a reply from her and 'ported close to the clearing and decided it would be better to change.

Blue light surrounded him and he hunched over. Loud cracks and pops of his bones extending, rearranging and changing into something different.

His clothing melted away, revealing his changing skeletal structure. His fingers and toes now bore sharp, wicked talons. His ribcage expanded and elongated, his shoulder blades shifting and popping out of place. The bones in his legs shifted, cracked and snapped into new shapes, forcing him to all fours. His tail grew and elongated. his head grew curved horns, protruding from his cheeks and forehead. His skull lengthened into a muzzle, his teeth growing large and sharp. Fangs jutted from his skull and grew past the length of his jaws. Wings grew from his back and expanded.

When the transformation was complete he let out an ear-splitting roar.

In the corner of his vision he saw crimson eyelights watching him from the shadows. He slowly turned hi head not taking his eyelights from his edgier counterpart. He slowly walked towards him but was stopped by something from the left.

Without warning he ran to his other startling him and causing him to fall over but he was in a protective stance and the other knew it. He was protecting him from something dangerous.

HELL HOUNDS

[(How I imagine them to look like)](https://www.pinterest.com/pin/504121752023515368/)

Wolf like monsters that were an experiment that got loose and found their way to Snowdin terrorizing those at night. They killed anything they come across that was alive and the only way to survive was to either hold your own against them and chase them away or climb up a tree as far as you could. 

They were hear now and that was not good. He also had to keep his counterpart safe.

 

This was going to be a nightmare........

**Notes for the Chapter:**

> How was the new chapter.  
> I will be correcting the mistakes in the last chapter and this chapter soon soon.

**Author's Note:**

> So guys how was the first chapter.????? I hope it was ok.
> 
> Slight spoiler but the reason they have higher stats has to do withtheresetstheybothremember. ; )
> 
> Just to let u guys now in advance I am a slow brighter so I won't be posting very often.
> 
> Till next tine guys cya.


End file.
